The semiconductor industry has experienced exponential growth. Continuous advancements in lithographic resolution have been made to support critical dimensions (CDs) of 90 nm to 65 nm, 45 nm, 32 nm, 22 nm, 16 nm and beyond. New techniques in lithography have been developed, such as immersion lithography, multiple patterning, extreme ultraviolet (EUV) lithography and e-beam lithography.
Dither is a well-known form of noise used to randomize quantization error, and error diffusion is one of the most popular algorithms to perform dithering. Error diffusion dithering is generally used to randomize quantization error for displaying or printing on substrates in various fields, such as electron beam lithography.
Current image dithering and error diffusion algorithms are mostly focused on minimizing visual artifacts. With the increase in integration density and the reduction in dimension of the integrated circuit (IC) devices, current methods have not been satisfactory in all respects. Therefore there is a need for an image dithering method to improve CD uniformity and to enlarge the process window of lithography processes.